Make sure that you select the right type of build.
!http://s7.postimg.org/f7i2hfokr/Untitled.png(build conf)!
Мassege:
"This does not seem to be a “Debug” build.
Setting breakpoints by file name and line number may fail."
is displayed only if you try debug in release mode.

Yes, I am very sure.Actually, I have two versions of Qt Creator, because when I downloaded "Qt 5.1.0 for Windows 32-bit (MinGW 4.8, OpenGL, 666 MB) (Info)" from download page, then I installed, I found Qt Creator is 2.7.2. Everything can work well on it. Next, I downloaded Qt Creator 2.8, I found I can't debug anything, I have tried to find what happened about it, but unfortunately I couldn't successful. I checked "Debugger Log" and I found something is different between two version of Qt Creator, but I still couldn't solve this problem.